Electrically actuated or electrically assisted steering system provide power assist to a steering assembly by providing a sleeve surrounding and threadingly engaged with a rack such that rotation of the sleeve by a motor imparts force to the rack, thereby assisting the driver in steering the vehicle. However, the force from the motor on the sleeve may result in high friction and excessive wear and tear.
In addition, electrically actuated or electrically assisted steering systems can produce noise that is heard by the driver. In particular, noise is produced in a rack assembly when the rotary mechanism of the motor is converted to linear motion by a ball-screw assembly. When the balls in the bearings and balls in the ball-screw move in the channels of the bearings and ball-screw, noise is created that is heard by the driver. As the vehicle travels on the roadway, impact of the road wheels on the roadway travels from the road wheels into the rack assembly. Bearings and related hardware must be sized such that loads due to such impact may be borne without exceeding exceptable noise levels. Such loading conditions may require component load bearing capability well above that required due to maximum system output.